Knife changing controls for paper cutting machines



Aug. 31, 1965 C. THUMIM 3,203,294

KNIFE CHANGING CONTROLS FOR PAPER CUTTING MACHINES ug. 3l, 1965 c. THUMIM 3,203,294

KNIFE CHANGING CONTROLS FOR PAPER CUTTING MACHINES Original Filed Deo. 9, 1960 2 Sheets-Sheet 2 m5. E

f l f LJ L 5% n', 3%,

/7/- /619 awk# V iwf Z Dwm/c-z E 7 Q, Z'

n wpd CO/VTQOL V04 7746.5

United States Patent O 3,203,294 KNIFE CHANGING CGNTROLS FOR PAPER CUTTING MACHINES Carl Thumim, Chicago, Ill., assigner to Miehle-Goss- Dexter, Incorporated, Chicago, Ill., a corporation of Delaware Original application Dec. 9, 1960, Ser. No. 74,993, now Patent No. 3,124,989, dated Mar. 7, 1964. Divided and this application Feb. 20, 1963, Ser. No. 259,899 6 Claims. (Cl. 83-399) This application is a division f my prior application S.N. 74,993 filed December 9, 1960, now Patent No. 3,124,989.

This invention relates to knife changing devices for use in guillotine type paper cutters and more particularly 4to an arrangement for effecting control during the course of the knife-changing procedure.

In modern practice in the use `of guillotine paper cutters, especially of the hydraulic powered clamp type, there has developed a system and an arrangement whereby the knife to be installed need not be raised or carried to the knife-bar by human effort, but can be temporarily attached to the clamp to be lifted up to the knife-bar for subsequent attachment thereto by means of screws.

In the course of changing the knives of guillotine paper cutters, it is essential that the knife-actuating mechanism be completely out of power operation and it is also essential that the knife being installed on the knife-bar be raised slowly so as to avoid shock stresses.

In general, the knife blade to be installed is carried on the clamp by means of a pair y0f washers which engage the knife bevel and hold it tightly against the front surface of the clamp. Such washers are normally carried in a particular storage place on the machine and are coupled with control circuitry. Thus, when the washers are removed. from storage and attached to the clamp for securing the knife thereto, the circuitry is operative to prevent knife-bar power actuation and also controls the clamp-actuating mechanism so as to raise it slowly, with the knife carried on it, to fully raised position to meet the knife bar. In prior art systems, generally, the clamp is raised by release of the foot treadle very cautiously so as to insure slow upward movement of the clamp. However, all operators do not have the necessary skill in foot treadle release in order to make certain that the knife is raised with sufficient slowness so as not to cause shock and stresses when it engages the knife-bar.

This particular problem of operator control has heretofore been dealt with by a system for reducing the pressure in `the clamp hydraulic system during the course of raising the clamp. However, there are certain drawbacks in such systems, in that uniform rates of upward travel cannot be obtained due to changes in friction values of the moving components. fFurther, mere pressure reduction does not, theoretically at least, result in reduced Yupward velocity of the clamp once it has started moving. This is due to the fact that the speed of the clamp is dependent on cylinder area and pump capacity, which are constant. Finally, mere reduction of pressure 'as a control expedient may not effect Isolid engagement of vthe knife against its seat in the knife bar.

It is an object of the present invention to provide a system which overcomes the drawbacks of prior art arrangements, as hereinabove described.

It is another object of the invention to provide a system which is safe in operation, economical t0 manufacture, and effective to provi-de reduced clamp speed in the course of knife-raising.

Briefly, my improved system effects clamp speed reduction by providing for restricted flow of oil from the exhaust end of the clamp pressure cylinder at the time rice the cylinder is in clamp-raising movement. Thus, by providing a reaction force that the clamp-raising piston must work against in raising the clamp, the speed of the clamp is necessarily reduced while at the same time full upward pressure is realized so that the clamp will force the knife solidly against its seat in the knife bar.

A detailed description of my invention will now be given in conjunction with the appended drawing, in which:

FIG. 1 is a schematic of the hydraulic circuit of the machine;

FIG. 2 is a schematic electrical diagram of the control circuit of the machine; and,

FIG. 3 is a plan view partially in section showing the storage device for the knife-holding washers.

Referring now to FIG. 1, a generally conventional hydraulic circuit, now known in the trade, and as shown in patent entitled Hydraulic Valves for Paper Cutter.

No detailed description of the hydraulic circuit is necessary except for such components as enter into coaction with certain novel components which constitute the present invention. Thus, there are the usual valves and clamp cylinder and piston, all as designated, and it will be noted that movement of the piston to the left effects upward movement of the clamp (not shown) while movement to the right effects downward movement. When the clamp is going down, the chamber 10 of the cylinder is filled via pipe 14 through a conventional prefill check valve while the chamber 18 exhausts via pipe 22 through the usual multiway solenoid-operated control valve 25. The dotted lines of the valve showing the down position.

Noted on FIG. 2 is the solenoid 25a which will be understood to control the clamp-operating valve 25.

There is provided the usual solenoid valve 28, the solenoid for which is shown as 28a in FIG. 2, and it will be understood that operation of valve 28 effects actuation of the throw-in cylinder, as shownin FIG 1, for alternately engaging the brake and clutch (not shown) for the knife-actuating mechanism (not shown) all of a conventional nature.

In order to simplify for the description of the present invention, additional explanation of what is already known and conventional is minimized therein, such information being unnecessary heretoand available in my prior patents and applications as hereinabove noted, in any event.

The particularly important feature of the present invention resides in the provision of a pilot operated check valve having the valve body 31 connected intermediate the ends of the cylinder via ducts 33, 34, as shown.A A solenoid operated normally open valve 36 having a solenoid 36a, as shown in FIG. 2, is connected in duct 34 connected to intermediate cylinder chamber 18 by way of connection to duct 22. Valve body 31 contains a, free piston 38 and a ball check valve 42, spring biased as shown, against its seat 42a. The casing 31 to the rear of ball check valve 42 is connected by a duct 4S via chan- 1 nel 45a to the chamber 47 intermediate piston 38 and ball check valve 42 and to the clamp operating solenoid valve 25. In the position shown, valve 25 is such that pressure fluid can pass chamber 18 for moving the clamp upwardly. When the clamp is up fluid from chamber 10 passes through valve body 31 behind the seated ball check 42 and out of the valve body via duct 45 to valve 25. A needle valve 50 in duct 45 meters the rate of ow from chamber 10 to Valve 25, from which valve oil passes to the tank via duct 52. Therefore, it will be apparent that according to the setting of the needle valve, the rate of exhaust from chamber 10 is determined, and the speed of the piston (and the clamp) goverened accordingly. The valve 36 being normally open, is closed only when it is desired to meter the exhaust from chamber 10 for slowing the rate of ascent of the clamp. Thus, with valve 36 open, pressure fluid passing through duct 22 will have a certain portion of its volume bypassed through valve 36 to push piston 38 to the left, thus unseating ball check 42. Accordingly, exhaust from chamber passes through the valve seat 42a into duct 45b without going through needle valve 50, and thus without restriction or metering, reaches valve 25 to exhaust to the tank. When, however, the normally open valve 36 is closed by actuation of solenoid 36a, pressure fluid in duct 22 cannot actuate piston 38 and the ball check valve 42 is spring-biased closed, thus forcing all uid exhausting from chamber 10 to pass through needle valve 50 which produces a resistance to movement of the clamp piston obviously slowing up the clamp.

Accordingly, although the clamp moves up slowly, full pressure is exerted, albeit at low discharge rate, and when the knife reaches the knife bar, it will be firmly seated thereagainst and held in place while the holding bolts are installed.

Referring now to FIG. 2, the schematic diagram for the electric control circuit shows a pair of push button switches which must be pressed simultaneously with both hands of the operator and designated as LH (left hand) and RH (right hand), all in accordance with conventional practice. When the switches are in released position as shown, it will be understood that the clamp is in its top position thereby causing closure of limit switch 60 to energize relay coil CR-8. All CR-8 contacts are then closed and remain closed. Depressing the push button switches serves to energize the coil of relay CR-13 whence all contacts CR-13 are closed and the clamp valve solenoid 25a is energized as well as the coil relay CR-10 and contacts CR-10 close. The effect of energization of the latter relay is to lock the clamp in downward position regardless of the position of the two-hand depressed operating switches. Thus, upon closure of contacts CR-10 and contacts CR-S, current always passes through clamp valve solenoid 25a and through the clamp valve limit switch 64 (the clamp being in upper position and closing this switch) so that depressing the push button switches and maintaining them depressed will pass current to knife valve solenoid 28a to effect downward movement of the knife bar by control of Valve 28 (FIG. l) and the brake-clutch throw-in cylinder. When the knife bar reaches the bottom of its stroke it closes limit switch 68 thereby maintaining the knife valve solenoid 28a energized so that the knife will complete its full cycle. At top position the knife bar opens limit switch 72 thus depressing all the relays and solenoids above-mentioned to stop the knife at the top of its stroke.

Further, the control of the clamp is such that upon starting downward movement, the clamp limit switch 76 closes so as to energize the solenoid 80 of the vent valve (shown in FIG. 1) to closed position, thereby permitting full pressure to be exerted on a paper pile when the clamp reaches it. At the same time that switch 76 closes the limit switch 60 opens and the clamp starts moving downwardly. Relay CR-S cannot be energized again until the clamp returns to its top position, thereby preventing recycling of the knife, even though the push buttons are again depressed during the cycling.

To the circuitry hereinabove generally described, is added a single pole double-throw switch designated in two part-s las Kel and K-2 which are controlled by the knife holding washers in a manner hereinbelow described but, from the diagram of FIG. 2, it will be noted that closure of K-l effects energization of the pilot valve solenoid 36a. At this time K-Z is open and it will be noted that this prevents current from passing to the push buttons so that it is not possible to cycle the knife. It will likewise be understood that closure of K-Z and opening of K-l deenergizes solenoid 36a, whence valve 36 of FIG. 1 is in its normally open position to unseat ball check valve 42 (FIG. l) while the contemporaneous condition of closure of Ke2 permits the energization of the knife operating cycle via the push buttons. It will also be noted that the open condition of K-2 disconnects the entire operating circuit so that the clamp, as well as the knife, cannot be operated by solenoid control. However, the clamp valve 25 can, in accordance with conventional machine construction, be operated by the machine foot treadle so as to effect the position of valve 25, as shown in solid lines in FIG. l, in order to provide pressure fluid to the clamp cylinder for raising the clamp.

FIG. 3 shows the knife-changing washer storage device which stores the washers so that upon removal, automatic actuation of switch elements K-l and K-2 is effected. Thus, the washers have screws 156 which are threaded into ysuitable threaded bores of the machine frame 158, at any desired place on the machine in ysome readily accessible area, and extend through the frame to engage respective threaded adjusting pins 162 which are carried in a teeter bar 165. The bar 165 is carried at its ends in slots 168 of the sides of a strap 171 of U-shaped formation bolted at its feet 174 to the fr-ame 158. Sidewise movement of teeter bar 165 is prevented by pins 1,77 carried thereby and engageable with the sides of the slots 168, as will be understood from FIG. 3. Thus, pins 177 are spaced slightly away from the sides of the slot to permit a predetermined degree of rocking of bar 165. Carried by the intermediate portion of the strap 171 is the switch larrangement K-l and K-2, generally designated by the housing 180 and shown in a diagrammatic manner as having a spring biased rod or pin 183 which resiliently abuts the center of bar 165 and maintains engagement of pins 177 with the washer screws. The rod 183 carries the center pole of the switch combination and it will be understood that when pin 183 is in the position shown K-1 is closed and K-Z is open to conform to the condition of FIG. 2. However, should either washer 155 be removed, the end of the bar 165 supported thereby will drop, thus dropping rod 183, whence K-1 will open and K-2 will close. The center pole of the switch as shown in FIG. 3, conforms, of course, to the direct connection shown between the two switches K-l, K-2 on FIG. 2.

An alternative arrangement would be to have switch K1 operated directly off the foot treadle so that any time the foot treadle is depressed, the clamp will slowly rise. Thus, the safety arrangement of FIG. 3 would involve only that portion of :the switch designated K-2. In such case, full release of the foot treadle would permit K-1 to open, for example, for rapid rise of the clamp.

Having thus described my invention, I am aware that Various changes may be made without departing from the spirit thereof and, accordingly, I do not seek to be limited to the precise illustrations herein given, except as set forth in the appended claims.

I claim:

1. In -a system of the class described, a lstorage device for knife holding elements comprising a supporting means, a rockable bar, a switch device, a pair of spaced holding elements carried by said supporting means, and said rockable bar being disposed between said holding elements at one side and said switch device at an opposite side and supported therebetween by opposed forces exerted thereby, wherein removal of one holding element effects rocking of said bar to actuate said switch device.

2. In a storage device as set forth yin claim 1, said rockable bar carrying adjusting elements abutting said holding elements for determining the initial .supported position of said bar.

3. In a system of the class described, `a pivotal bar element, resilient means acting centrally on said bar element in one direction, a pair of knife lholding elements acting on said bar element in an opposite direction, wherein said bar element is normally maintained in a predetermined position, support means for said knife holding elements and means whereby said knife holding elements may be stored in or removed from said lsupport means, and switch means operatively disposed to be actuated when said bar element moves away from said pre-,

determined position upon removal of one of said knife holding elements.

4. In a system as set forth in claim 3, said resilient means comprising a housing having a pin reciprocally mounted therein and extending therefrom and having a spring therein biasing said pin to abut said bar, said switch means comprising a switch element carried by said pin and a coacting switch element engageable thereby responsive to movement of said pin when said bar is moved from said predetermined position.

5. In ya system as set forth in claim 4, said bar carrying adjusting elements abutting said knife holding elements for eiecting said initial predetermined position of said bar.

6. In a system of `the class described, a circuit controlling storage device for knife-holding means, comprising a switch, a pair of spaced knife-holding means, a movable element disposed to be held in predetermined position relative to said switch by said pair of knife-holding means, whereby removal of either knife-holding means is operative to effect motion of said element to actuate said switch, said movable element being connected to said switch to hold said switch in normally non-actuated condition.

References Cited by the Examiner UNITED STATES PATENTS 6/60 Haywood 83-453 

6. IN A SYSTEM OF THE CLASS DESCRIBED, A CIRCUIT CONTROLLING STORAGE DEVICE FOR KNIFE-HOLDING MEANS, COMPRISING A SWITCH, A PAIR OF SPACE KNIFE-HOLDING MEANS, A MOVABLE ELEMENT DISPOSED TO BE HELD IN PREDETERMINED POSITION RELATIVE TO SAID SWITCH BY SAID PAIR OF KNIFE-HOLDING MEANS, WHEREBY REMOVAL OF EITHER KNIFE-HOLDING MEANS IS OPERATIVE TO EFFECT MOTION OF SAID ELEMENT TO ACTUATE SAID SWITCH, SAID MOVABLE ELEMENT BEING CONNECTED TO SAID SWITCH TO HOLD SWITCH IN NORMALLY NON-ACTUATED CONDITION. 